PyADS Tutorial 😀

This notebook aims to help you learn PyADS and how it help be helpful to you!~

Prerequisites

  • Basic programming knowledge 📘
  • Good skills in copy and pasting 📗
  • Completing the Python for Noobs Guide would be nice, but not necessary 🐍

Let's get started! 📕

⚡Installation ⚡

image.png

Ensure you have some sort of Python IDE installed on your machine. I recommend PyCharm Community Edition. It's free and open-source and very user friendly. If it's youre first time installing a Python IDE, ensure you select the "Add to PATH" checkbox. ✅

https://www.jetbrains.com/pycharm/download/#section=window

output-onlinepngtools.png

Alternatively, you can use VS-Code. It's a more lightweight text editor but requires more configuration. It also allows you to run C#, C++ and Java code, and also allows you to code in ST if you install the extension pack. ⛪

https://code.visualstudio.com/Download

🐍Getting Started with Python🐍

Let's get down to business

Create a new Python Project in Pycharm using a Virtual Enviornment 🍀

image.png image.png

Congratulations! You've created your first Python Project 👏👏👏

Let's create a Python File 🐍

image.png

Right click the folder path (AKA, your project name, NOT venv) and create a new Python File. For me I called it ADSfirstTime.py

image.png image.png

Now, you should see a blank .py file appear!

image.png

📦Installing PyADS package📦

Congratulations! You're just ONE step away from writing some PyADS code. All we gotta do now is INSTALL THE PYADS PACKAGE!

On the bottom of the screen, select on terminal

image.png

Then, type in the following command:

pip install pyads

image.png

Then, press ENTER and let it do its ✨magic✨

For context, pip is a package manager that allows you to download open-source python packages from the internet. 🧑

If an error pops up saying that pip is outdated, ignore it and continue 💅

Connecting to PLC

🍳 Let's start cooking up some PyADS code! 🍳

Firstly, we would need to reference the pyads package. So let's use an import statement! 🛬

import pyads

Next, we would need to reference our PLC via it's AMSNETID. We can store it as a STRING 🧣

AMSNETID = "10.123.67.6.1.1"

Following that, we have to instantiate our pyads connection and open the connection using the following lines of code. 📠

plc = pyads.Connection(AMSNETID, pyads.PORT_TC3PLC1)
plc.open()
print(f"Connected?: {plc.is_open}") #debugging statement, optional
print(f"Local Address? : {plc.get_local_address()}") #debugging statement, optional

If you're lazy, like me, and just want the whole code, here it is!

import pyads

AMSNETID = "10.123.67.6.1.1"
plc = pyads.Connection(AMSNETID, pyads.PORT_TC3PLC1)
plc.open()
print(f"Connected?: {plc.is_open}")
print(f"Local Address? : {plc.get_local_address()}")
print(plc.read_state())

If you're running this on localhost, make sure TWINCAT XAE is online and logged in! I assume this is self-explainatory.

image.png

If all goes well, you can run the script you've written so far.

Right click on the tab you're on in Pycharm and click run!

image.png

If you've followed well in this tutorial, you should get the following output!

image.png

If there are any problems, feel free to approach me! 😀

Reading and Writing Values

You've been writing python code for the past 15 minutes, you can pat yourself on the back! 👏

Let's get into cooler things. Reading and writing values. 😎

Let's create some variables in TwinCat to manipulate! ❗

In TwinCat, create a new GVL

image.png

Let's create some variables! ♟

{attribute 'qualified_only'}
VAR_GLOBAL
    bOut1: BOOL;
    bOut2: BOOL;
END_VAR

Under the MAIN POU,

image.png

In the initialization menu:

PROGRAM MAIN
VAR
    out1: BOOL;
    out2: BOOL;
    bDummy : BOOL;

END_VAR

In the main program:

out1 := GVL.bOut1;
out2 := GVL.bOut2;

This is how it should look like as of now!

image.png

Rebuild the solution, activate config and log in with online changes (I assume this is self-explainatory)

Reading GVL from PyADS

Here's the basic syntax of reading values though PyADS 💥

var = plc.read_by_name("NAMEOFVARIABLE")

Insert the following lines of code in your python script in addition to your previously written script. 📓

bOut1 = plc.read_by_name("GVL.bOut1")
print(f"bOut1 State {bOut1}")
plc.close()

Here's the whole program so far! 🤓

import pyads

AMSNETID = "10.123.67.6.1.1"
plc = pyads.Connection(AMSNETID, pyads.PORT_TC3PLC1)
plc.open()
print(f"Connected?: {plc.is_open}")
print(f"Local Address? : {plc.get_local_address()}")
print(plc.read_state())

bOut1 = plc.read_by_name("GVL.bOut1")
print(f"bOut1 State {bOut1}")

plc.close()

Run the script and watch the ✨ magic ✨ happen~

Cross refer your GVL value and your python-read value. Are they the same? 🤔

image.png image.png

If they are, congratulations! You've read your first value in the PLC through PyADS. You've made it this far! Now all thats left is to write values into the PLC!

Writing GVL from PyADS

The basic syntax to write values into the PLC is as follows: 💥

plc.write_by_name("VARIABLENAME", REPLACEMENTVALUE)

Note: They have to be of the same data type!!! 🎓

Insert the following lines of code into your project

plc.write_by_name("GVL.bOut1", True) #overrride values

bOut1 = plc.read_by_name("GVL.bOUt1") #reads to confirm 
print(f"Final State {bOut1}")

This is how your code should look like so far. (From the top till now)

import pyads

AMSNETID = "10.123.67.6.1.1"
plc = pyads.Connection(AMSNETID, pyads.PORT_TC3PLC1)
plc.open()
print(f"Connected?: {plc.is_open}")
print(f"Local Address? : {plc.get_local_address()}")
print(plc.read_state())

bOut1 = plc.read_by_name("GVL.bOut1")
print(f"bOut1 State {bOut1}")


plc.write_by_name("GVL.bOut1", True)

bOut1 = plc.read_by_name("GVL.bOUt1")
print(f"Final State {bOut1}")

plc.close()

Run the code to watch some more ✨magic✨!

image.png image.png

Common mistake- closing the plc connection before the end of the script. Did you commit the same mistake?

Final Chapter: Reading and writing into local variables

Reading and writing into variables can be done in the same way we write into GVLs. We just need to reference the POU or PRG we want to change. 🤫

In the main program, make 2 new variables: ⏰

iNumber: INT;
sWord: STRING;

If you're an avid user of Ctrl-C Ctrl-V, here's the entire initialisation script so far: 🤓

PROGRAM MAIN
VAR

out1: BOOL;
out2: BOOL;
bDummy : BOOL;
iNumber: INT;
sWord: STRING;

END_VAR

Notice how we have 5 local variables now, but 2 are linked to GVLs

In order to test our program, we can do the following

  • Read the state of the variable BEFORE writing 👓
  • Write a value into the variable ✏
  • Confirm the state of the variable by Reading AGAIN! 👓

That's gonna take a huge amount of copying and pasting, so let's write a function to do it for us! 🤓

def readAndWrite(plcInput, variable, state):
    print(f"For variable {variable}:")
    print("before writing: ",plcInput.read_by_name(variable))
    plcInput.write_by_name(variable, state)
    print("after writing: ",plcInput.read_by_name(variable), '\n')

We'll be using this function repeatedly in the following code sample.

Copy and paste this completed code sample! 👍

import pyads

AMSNETID = "10.123.67.6.1.1" #change to what you need
plc = pyads.Connection(AMSNETID, pyads.PORT_TC3PLC1)
plc.open()
print(f"Connected?: {plc.is_open}")
print(f"Local Address? : {plc.get_local_address()}")
print(plc.read_state())

def readAndWrite(plcInput, variable, state):
    print(f"For variable {variable}:")
    print("before writing: ",plcInput.read_by_name(variable))
    plcInput.write_by_name(variable, state)
    print("after writing: ",plcInput.read_by_name(variable), '\n')

readAndWrite(plcInput = plc, variable = "MAIN.bDummy", state = True)
readAndWrite(plcInput = plc, variable = "MAIN.iNumber", state = 69)
readAndWrite(plcInput = plc, variable = "MAIN.sWord", state = "Hello World!")
readAndWrite(plcInput = plc, variable = "GVL.bOut1", state = True)
readAndWrite(plcInput = plc, variable = "GVL.bOut2", state = True)

plc.close()

Take note of the previous values in TwinCat

image.png

Now run the script and look at the console output and TwinCat

C:\Users\MaxwellA.BECKHOFF\PycharmProjects\FirstPorject\venv\Scripts\python.exe C:/Users/MaxwellA.BECKHOFF/PycharmProjects/FirstPorject/ADSfirstTime.py
Connected?: True
Local Address? : <AmsAddress 10.123.67.6.1.1:32929>
(5, 0)
For variable MAIN.bDummy:
before writing:  False
after writing:  True 

For variable MAIN.iNumber:
before writing:  0
after writing:  69 

For variable MAIN.sWord:
before writing:   
after writing:  Hello World! 

For variable GVL.bOut1:
before writing:  True
after writing:  True 

For variable GVL.bOut2:
before writing:  False
after writing:  True 


Process finished with exit code 0

image.png

THATS ALL FOLKS!!

If you have any more questions, feel free to ask me :D

lol.gif